A new straightforward formation of aminoisoxazoles from isocyanides

The reaction of α-bromoketone oximes with isocyanides and sodium carbonate leads to a new formation of 5-aminoisoxazole derivatives. The reaction probably involves the intermediacy of a nitrosoalkene generated in situ. Good yields are obtained for electron deficient ketone oximes such as ethyl bromopyruvate oxime; the use of a trifluoromethyl substituted oxime gives a high efficient formation of trifluoromethyl isoxazoles.